Are Cold Waves Increasing Under Global Warming

The coldest temperatures of the winter have hit the eastern U.S. and misinformation is now spreading around social and traditional media.

President Trump, of course, tweets about the cold wave, suggesting that global warming has left us, and hopes for its return:

And then a number of supposedly reputable media outlets, like the NY Times and the WA Post, are giving play to the hypothesis that global warming is causing more cold waves, through the "lazy jet stream" mechanism pushed by Dr. Jennifer Francis of Woods Hole and Dr. Jacob. of a private sector firm, ERT.   


Let's clarify this once and for all:  the observational evidence is very clear:  there are LESS cold waves today than in the past, which is exactly what we would expect in a warming world.

The U.S.  Environmental Protection Agency did a study of the trend of cold wave days over the past 50 years.   The found very few locations where cold waves were becoming more frequent, but lots of locations in the western U.S. and the East Coast where cold waves were become less frequent, with the West Coast have a huge decline of cold waves (see below).

A plot of the area in the U.S. covered by cold periods (again by EPA) shows a decided decline in cold daily lows.

And a plot of the percent of daily record highs are increasing, but daily lows are decreasing since the 1970s (again from EPA).

from Cliff Mass Weather and Climate Blog http://bit.ly/2WtoBjh